From the Swedish patent specification No. 353,210 it is known to provide irrigation apparatus connected to a water pipe with an automatic regulating device by means of which irrigation is coupled in for periods with adjustable length broken by waterless periods with a length dependent on the relative humidity of the surrounding air.
The known device comprises a main valve with a valve body formed as a differential piston having a small-bore central through duct to its major side a duct from this major side to a control valve which is arranged to close and open the main valve when it closes and opens said duct, as well as a pivoting means with an open bowl arranged to be supplied with water from a drop means controlled by the control valve and, as soon as the supplied amount of water has reached a limiting value to tip over and thereby actuate the control valve by a projecting portion such that it closes the main valve and the water flow to the drop means, keeping them closed until sufficient water has evaporated from the bowl so that the tipping means tips back again, the projecting portion disengaging the control valve so that the latter reopens the main valve and the water flow to the drop means.
It has been found desirable to arrange that irrigation takes place substantially at night, and that the length of the waterless periods will also be dependent on rainfall.
The present invention relates to a method fulfilling precisely these desires and an apparatus for carrying out the method.
The invention is described in detail hereinafter.